Method and apparatus for withdrawing continuous horizontal castings

ABSTRACT

The continuous casting is pulled from the mold by sequentially engaging the movable withdrawal tables on the casting and pulling the casting with the engaged withdrawal table. The withdrawal tables operate in unison with each other so that as one pulls the casting, the other retreats for a subsequent pull.

United States Patent Inventor Alfred J. Wertli Poststr. CH, 8406 Winterthur, Switzerland Appl. No, 593,810 Filed Nov. 14, 1966 Patented Feb. 16, 1971 Priority Nov. 15, 1965 Switzerland 15689/65 METHOD AND APPARATUS FOR WITHDRAWING CONTINUOUS HORIZONTAL CASTINGS 10 Claims, 3 Drawing Figs.

US. Cl 164/82, 164/154, 164/282 Int. Cl B22d 11/12 Field ofSearch.... 164/82, 89, 282, 283, 154

References Cited UNITED STATES PATENTS H Iislgus et a1... 164/155 648,091 4/1900 Trotz 164/283 1,088,171 2/1914 Pehrson.... 164/282X 1,422,532 7/1922 Breit 164/282X 3,107,404 10/1963 Armand et al. 164/282X FOREIGN PATENTS 569,367 11/1957 Italy 164/84 812,356 4/1959 Great Britain... 164/82 895,913 5/1962 Great Britain 164/282 Primary Examiner.l. Spencer Overholser Assistant Examiner-R. Spencer Annear Allurney- Kenyon & Kenyon, Reilly, Carr & Chapin ABSTRACT: The continuous casting is pulled from the mold by sequentially engaging the movable withdrawal tables on the casting and pulling the casting with the engaged withdrawal table. The withdrawal tables operate in unison with each other so that as one pulls the casting, the other retreats for a subsequent pull.

METHOD AND APPARATUS FOR WITHDRAWING CONTINUOUS HORIZONTAL CASTINGS This invention relates to continuous casting of metals. More particularly, this invention relates to an apparatus and method for continuous casting of metals and still more particularly to the continuous or intermittent movingof a casting from a mold connected to a furnace.

Heretofore, in continuous casting of metals, a metal melted within a furnace has been cast in at least one mold connected to the furnace and the cast strand had been moved or pulled from the mold either continuously or intermittently by a pair of clamping members, for example in the fonn of, clamping jaws. However, the clamping jaws have been used to move the cast strand in a series of interrupted strokes. That is, after moving the engaged cast strand a distance equal to a stroke length, the clamping jaws have been released from the cast strand at the end of each stroke and returned a distance equal to the stroke length for reengagement with the cast strand to ,again move the strand another stroke length away from the furnace and mold. Because of the time required for the return movement of the clamping jaws after each stroke, only limited continuous casting speeds have been achieved, for example, 40 strokes per minute. In addition, the homogeneity of the structure of the cast metal has not always been satisfactory.

Briefly, the invention obtains a cast strand of very uniform structure by pulling the strand from the mold at a substantially high number of short strokes per unit time, for example, at 200 strokes or pulls per minute. The apparatus of the invention includes at least two withdrawal tables having a pair of clamping jaws on each which are disposed so as to sequentially engage and pull a cast strand from a mold. Each pair of clamping jaws is reciprocally movable in the direction of the cast metal in one or more strokes and is correlated to the other pair of clamping jaws so that the movements of each are controlled with respect to each other. In operation, as the pair of clamping jaws of one withdrawal table engages and moves the cast strand the pair of clamping jaws of the other withdrawal table disengages and returns to the initial starting position for reengagement with the cast strand. Each pair of clamping jaws can move the cast strand in one long pull or stroke or in several successive small strokes before the other pair of clamping jaws engages the cast strand. The distance traveled by a pair of clamping jaws moving in engagement with the cast strand before being disengaged is sufficient to allow the other pair of clamping jaws to return to the initial starting position for reengaging the cast strand. The period of motion and the period of rest of the cast strand within a cycle as well as the length of the cycle are capable of being varied in a simple manner so that the operation of the apparatus can be adapted to the properties of the metal and metal alloys being cast. In addition, these variations can be carried out during operation of the apparatus. Also, in addition to moving the cast strand in a series of pulls within a stroke of the clamping jaws, the cast strand can be continuously moved.

The method of the invention includes the steps of moving the cast strand in a continuous manner fromthe mold connected to the furnace at a high rate of strokes per unit time with each stroke being of a length smaller than the smallest dimension of the cross section of the metal being cast to obtain a satisfactory homogeneous structure in the cast strand.

Accordingly, it is an object of the invention to provide an apparatus and method for continuously casting metals at a high rate of short strokes per unit time.

It is another object of the invention toprovide an apparatus and method for moving a cast strand from a mold connected to a furnace in a continuous manner in a consecutive series of strokes of smaller length than the smallest cross-sectional dimension of the cast strand.

It is another object of the invention to obtain a cast strand of homogeneous structure.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which: i

FIG. 1 illustrates a diagrammatic view of an apparatus according to the invention;

FIG. 2 is illustrates a modification of a control for the apparatus of FIG. 1; and

FIG. 3 illustrates a diagrammatic representation of an intermittent movement of a cast strand as a function of time according to the invention.

Referring to FIG. 1, a furnace 1 containing molten metal has at least one mold 2 for molding a metal casting from the molten metal connected to an outlet and a cooling device 3 surrounding the mold 2 for cooling the molten metal in the mold 2. A pair of withdrawal tables 4,5 and a roller track (not shown) are aligned with the mold 2 to move a cast strand 6 from the furnace l and mold 2. The molten metal in the furnace l flows into the mold 2, is cooled therein by the cooling device 3 to a solidified state and leaves the mold as a cast strand 6 in the direction indicated by the arrow 7.

In the following description the withdrawal table 4 will be described, the corresponding parts of the other withdrawal table 5 being given the same reference numerals together with a primed mark. The withdrawal table 4 has a pair of clamping jaws 8 which can be pressed into gripping engagement against the casting 6 and released therefrom by conventional means, e.g. by hydraulic means. The withdrawal tables 4 and 5 are reciprocally movable on a base 9 rectilinearly in the longitudinal direction of movement of the cast strand 6 i.e. of the cast strand. The withdrawal table 4 is rigidly connected to a piston 10 which is reciprocally movable in a cylinder 11 parallel to the longitudinal axis of the cast strand 6. A pressure medium feed pipe 12 is connected to cylinder 11 on one side of the piston 10 and to a change over valve 1.3 of a pressure medium feed system. In addition, a pipe 14 is also connected to the cylinder 11 on the other side of the piston 10 to communicate with a separate similar pressure medium feed system (not shown). The change over valve 13 is likewise connected via a pipe 12' to the cylinder 11' on one side of the piston 10' to which a pipe 14' of the separate pressure medium feed system is also connected on the other side of the piston 10'.

Limit switches 15, 15' are provided on the base 9 to cooperate with earns 16, 16' mounted on the withdrawal tables 4, 5. At the ends of the pulling movements or strokes of the withdrawal tables 4, 5 the limit switches 15 and 15' activate the change over valve 13. The pressure medium feed pipes 12, 12' are fed by a pump 17 which draws pressure medium from a reservoir 18 and feeds the medium to the change over valve 13 via va valve 19 and a flow control member 20.

In the position shown of the change over valve, the pressure medium is being fed to the cylinder 11 via the pipe 12, e.g. at a pressure of 100 p.s.i., as a result of which the piston 10 and thus the withdrawal table 4, the clamping jaws 8 of which are in gripping engagement with the casting 6 are moved intermittently as described below in the direction indicated by the arrow 7. Since a lower pressuregfor example, 40 p.s.i. is exerted in the pipe 14 the pressure medium on this side of the piston 10 escapes from the cylinder 11. During this movement of the withdrawal table'4, the withdrawal table 5 is moved by the pressure medium in the pipe 14' via the piston 10' opposite to the direction indicated by the arrow 7 back to its initial position; the clamping jaws 8" being released from the casting 6 as shown in the drawing. The pressure medium present on the left side of the piston 10' as viewed in FIG. 1 flows via a pipe (not shown) into the reservoir 18. When the withdrawal table 4, after having carried out, for example, 20 or 30 intermittent strokes or pulls, actuates the limit switch 15 through the cam 16, the change over valve 13 is reversed so that the pressure medium fed by the pump 17 flows via the pipe 12' into the cylinder 11' and intermittently moves the withdrawal table 5 in the direction indicated by the arrow 7 in I a plurality of successive strokes or pulls. Simultaneously with the reversing of the valve 13, the clamping jaws 8' of table 5 grip the casting 6 while the clamping jaws 8 of table 4 are released therefrom. The withdrawal table 4 is then returned,

by means of the pressure medium in the pipe 14 to its initial position, as has been described above for the withdrawal table 5.

The flow control valve 20 operates to adjust the quantity of pressure medium being fed to the pistons or 10' at a given time while the valve 19 operates to control the intermittent movement of the withdrawal tables 4 and 5 through a rotatable cam 21 which opens and closes the valve periodically. The cam is driven by a gear (not shown), the number of revolutions of which is variable, and a motor (likewise not shown).

Referring to FIG. 3, the length T of a cycle can be varied by varying the number of revolutions of the gear driving the cam 21 while the period of motion and the period of rest within each cycle may be varied by changing the cam 21 for a cam of a different shape. For example, a ratio of the period of motion to the period of rest B/R 1:2 can be adjusted to B'IR 3:1. Also, replacing the cam 21 by a disc with a cylindrical circumference, a continuous movement of the withdrawal tables 4 and 5 can be achieved.

Referring to F IG. 2, a solenoid valve 22 is provided in place of the cam-controlled valve 19 to control the feed of the pressure medium and is controlled by an impulse generator 23. The impulse generator 23 also varies the length of the cycle, the period of motion and the period of rest in a simple manner.

Having thus described the invention, it is not intended that it be so limited as changes may be readily made therein without departing from the scope of the invention. Accordingly, it is intended that the subject matter described above and shown in the drawings be interpreted as illustrative and not in a limiting sense.

lclaim:

1. An apparatus for continuouslycasting metals horizontally comprising:

a furnace for containing molten metal;

a mold connected to said furnace for molding said molten metal into a cast strand; at least a pair of fluid-actuated reciprocally movable withdrawal tables, each withdrawal table having a pair of clamping jaws mounted thereon in alignment with the cast strand for releasably gripping the cast strand; and

control means for reciprocally moving said withdrawal tables in opposed rectilinear directions axially of the cast strand simultaneously to continuously pull the cast strand from said mold in intermittent strokes, said control means having valve means for moving one of said withdrawal tables away from said mold with said clamping jaws thereon in gripping engagement with the cast strand while moving said other withdrawal table towards said mold with said clamping jaws thereon out of gripping engagement with the cast strand.

2. An apparatus as set forth in claim 1 which further includes a limit switch at the end of 'the path of movement of each withdrawal table for actuating said control means to reverse the direction of movement of each said withdrawal tables.

3. A method for continuously casting metals including the steps of:

molding a molten metal into a cast strand;

gripping the cast strand with a fluid-actuated first withdrawal table;

moving the gripped cast strand in a series of rectilinear intermittent strokes in a first horizontal path of movement axially of the cast strand, by periodically opening and closing a fluid control valve;

subsequently releasing the cast strand from the first gripping table; 1

thereafter gripping the cast strand with a fluid-actuated second withdrawal table;

withdrawal table and thereafter regripping the cast strand with the first withdrawal table to move the strand in a further series of intermittent steps in said path of movement; and

repeating said steps in sequential fashion to obtain a homogeneity of structure in the cast strand.

4. An apparatus as set forth in claim 1 wherein said control means includes:

a pair of pistons, each piston being connected to a respective one of said withdrawal tables;

a first pressure medium feed system operably connected to one side of each said piston for delivering pressure medium to selectively move one of said pistons away from said mold; and

a second pressure medium feed system operably connected to the opposite side of each piston for delivering pressure medium to selectively move the other of said pistons toward said mold.

5. An apparatus as set forth in claim 4 wherein at least one of said feed systems includes a changeover valve therein for selectively directing a flow of pressure medium to one of said pistons.

6. An apparatus as set forth in claim 5 which further comprises a switch means at the end of the path of movement of each withdrawal table operatively connected to said changeover valve for actuating said changeover valve to direct a flow of pressure medium from one of said pistons to the other of said pistons.

7. An apparatus as set forth in claim 4 which further includes means in at least one of said feed systems for varying the supply of pressure medium delivered to said pistons to intermittently move said withdrawal tables.

8. A method as set forth in claim 3 wherein the cast strand is moved in a series of intermittent short strokes of a length less than the smallest cross sectional dimensions of the cast strand.

9. An apparatus as set forth in claim 1 further including means for actuating said control means to move said withdrawal tables having said clamping jaws thereof gripping the cast strand in a plurality of intermittent steps to intermittently move the cast strand.

10. In combination with a furnace having a mold for molding a molten metal in said mold into a cast strand, an apparatus for continuously pulling the cast strand horizontally from said mold comprising:

a pair of fluid-actuated reciprocally movable withdrawal tables each having a pair of clamping jaws mounted thereon in alignment with the cast strand for releaseably gripping the cast strand;

means for sequentially moving said pairs of said clamping jaws with respect to the cast strand wherein one of said pairs of jaws is released from gripping of the cast strand and the other of said pair of jaws is thereafter brought into gripping relation with the cast strand; and

control means for reciprocally moving said withdrawal tables in sequential order axially relative to the cast strand to pull the cast strand in a continuous series of strokes from said furnace, said control means having valve means for moving one of said withdrawal tables rectilinearly away from said mold with said clamping jaws thereon in gripping engagement with the cast strand while said other withdrawal table is free to move independently thereof towards said mold with said clamping jaws thereon out of gripping engagement with the cast strand. 

1. An apparatus for continuously casting metals horizontally comprising: a furnace for containing molten metal; a mold connected to said furnace for molding said molten metal into a cast strand; at least a pair of fluid-actuated reciprocally movable withdrawal tables, each withdrawal table having a pair of clamping jaws mounted thereon in alignment with the cast strand for releasably gripping the cast strand; and control means for reciprocally moving said withdrawal tables in opposed rectilinear directions axially of the cast strand simultaneously to continuously pull the cast strand from Said mold in intermittent strokes, said control means having valve means for moving one of said withdrawal tables away from said mold with said clamping jaws thereon in gripping engagement with the cast strand while moving said other withdrawal table towards said mold with said clamping jaws thereon out of gripping engagement with the cast strand.
 2. An apparatus as set forth in claim 1 which further includes a limit switch at the end of the path of movement of each withdrawal table for actuating said control means to reverse the direction of movement of each said withdrawal tables.
 3. A method for continuously casting metals including the steps of: molding a molten metal into a cast strand; gripping the cast strand with a fluid-actuated first withdrawal table; moving the gripped cast strand in a series of rectilinear intermittent strokes in a first horizontal path of movement axially of the cast strand, by periodically opening and closing a fluid control valve; subsequently releasing the cast strand from the first gripping table; thereafter gripping the cast strand with a fluid-actuated second withdrawal table; moving the gripped cast strand in a subsequent series of rectilinear intermittent steps in said path of movement by periodically opening and closing a fluid control valve; subsequently releasing the cast strand from the second withdrawal table and thereafter regripping the cast strand with the first withdrawal table to move the strand in a further series of intermittent steps in said path of movement; and repeating said steps in sequential fashion to obtain a homogeneity of structure in the cast strand.
 4. An apparatus as set forth in claim 1 wherein said control means includes: a pair of pistons, each piston being connected to a respective one of said withdrawal tables; a first pressure medium feed system operably connected to one side of each said piston for delivering pressure medium to selectively move one of said pistons away from said mold; and a second pressure medium feed system operably connected to the opposite side of each piston for delivering pressure medium to selectively move the other of said pistons toward said mold.
 5. An apparatus as set forth in claim 4 wherein at least one of said feed systems includes a changeover valve therein for selectively directing a flow of pressure medium to one of said pistons.
 6. An apparatus as set forth in claim 5 which further comprises a switch means at the end of the path of movement of each withdrawal table operatively connected to said changeover valve for actuating said changeover valve to direct a flow of pressure medium from one of said pistons to the other of said pistons.
 7. An apparatus as set forth in claim 4 which further includes means in at least one of said feed systems for varying the supply of pressure medium delivered to said pistons to intermittently move said withdrawal tables.
 8. A method as set forth in claim 3 wherein the cast strand is moved in a series of intermittent short strokes of a length less than the smallest cross sectional dimensions of the cast strand.
 9. An apparatus as set forth in claim 1 further including means for actuating said control means to move said withdrawal tables having said clamping jaws thereof gripping the cast strand in a plurality of intermittent steps to intermittently move the cast strand.
 10. In combination with a furnace having a mold for molding a molten metal in said mold into a cast strand, an apparatus for continuously pulling the cast strand horizontally from said mold comprising: a pair of fluid-actuated reciprocally movable withdrawal tables each having a pair of clamping jaws mounted thereon in alignment with the cast strand for releaseably gripping the cast strand; means for sequentially moving said pairs of said clamping jaws with respect to the cast strand wherein one of said pairs of jaws is released from gripping of the cast strand and the other of said paIr of jaws is thereafter brought into gripping relation with the cast strand; and control means for reciprocally moving said withdrawal tables in sequential order axially relative to the cast strand to pull the cast strand in a continuous series of strokes from said furnace, said control means having valve means for moving one of said withdrawal tables rectilinearly away from said mold with said clamping jaws thereon in gripping engagement with the cast strand while said other withdrawal table is free to move independently thereof towards said mold with said clamping jaws thereon out of gripping engagement with the cast strand. 